Solid-state synthesis and characterization of polyaniline/multi-walled carbon nanotubes composite

The polyaniline/multi-walled carbon nanotubes (PANI/MWNTs) composites with content of MWNTs varying from 8 wt% to 32 wt% were prepared by a novel solid-state synthesis method. The structure and morphology of the composites were characterized by the Fourier transform infrared (FTIR) spectroscopy, Raman spectroscopy, ultraviolet–visible (UV–vis) absorption spectroscopy, X-ray diffraction (XRD), scanning electron microscopy (SEM) and transmission electron microscopy (TEM). The electrochemical performances of the composites were investigated by galvanostatic charge–discharge measurement, cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS). The results from FTIR spectra showed that the composites display a higher oxidation degree than PANI, and the composite with 16 wt% MWNTs has the highest intensity ratio of quinoid to benzenoid ring modes. The UV–vis and Raman spectra revealed that the some interaction between the PANI and MWNTs occurred in the composites. The result from XRD revealed the presence of MWNTs in the polymer matrix. And the morphological studies showed that the composite with 16 wt% MWNTs displayed nano-sized granular-like particles with spongy and highly porous morphology, while the composite with 32 wt% MWNTs displayed rod-like features. The galvanostatic charge–discharge measurements indicated that the PANI/MWNTs composites had higher specific capacitances than PANI. The composite with 16 wt% MWNTs had the highest specific capacitance among the composites. The further electrochemical tests on the composite with 16 wt% MWNTs showed that the composite displayed an ideal capacitive behavior and good rate ability.